External Monitor Question

So I recently purchased this incredible Dell external monitor, however when connected to my Macbook Pro, I am unable to work on the monitor without the laptop being open. Is there any way I can adjust it so the laptop doesn't need to be open for me to use the external?

You don't want your MBP closed due to the heat ventilation. So I closed it, turned off the external display, then clicked on my keyboard, turned on the external, and opened the MBP. So my external is working and the MBP is open but off.

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